U.S. patent number 4,902,666 [Application Number 07/142,892] was granted by the patent office on 1990-02-20 for process for the manufacture of spheroidal bodies by selective agglomeration.
This patent grant is currently assigned to Chevron Research Company. Invention is credited to Andrew Rainis.
United States Patent |
4,902,666 |
Rainis |
February 20, 1990 |
Process for the manufacture of spheroidal bodies by selective
agglomeration
Abstract
This invention relates to the preparation of small spheroidal
solid agglomerates. More particularly, the process produces strong
solid spheroidal agglomerates containing alumina or a mixture of
alumina and at least one other inorganic material, which process
comprises: (a) mixing at high speed a portion of alumina or a
mixture of alumina and at least one other inorganic material in the
form of hydrophilic mircon-sized particles in a water-immiscible
liquid thereby forming a dispersion; (b) gradually adding to the
dispersion an aqueous acidic phase while continuing the high-speed
mixing until substantially spherical micro-agglomerates form within
the water-immiscible liquid; (c) subjecting the micro-agglomerates
to agitation in a vessel having a hydrophobic inner surface at a
speed low enough to achieve substantially uniformly sized
spheroidal agglomerates; (d) drying the agglomerates to produce
hardened spheroidal uniformly sized agglomerates; and (e)
optionally further separating the agglomerates by size. Optionally,
the aqueous phase in step (b) may include the soluble salts of
catalytic metals, and bases and/or colloidal-sized inorganic
particles. These spheroidal particles can have either smooth
surfaces or polylobe surfaces depending on the conditions of
preparation. They have diameters generally between 1 to 5 mm and
are useful as catalysts, or catalyst supports. Catalytic components
may subsequently be deposited on the support.
Inventors: |
Rainis; Andrew (Walnut Creek,
CA) |
Assignee: |
Chevron Research Company (San
Francisco, CA)
|
Family
ID: |
26840516 |
Appl.
No.: |
07/142,892 |
Filed: |
January 11, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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881156 |
Jul 2, 1986 |
4737478 |
|
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Current U.S.
Class: |
502/439; 423/335;
423/625; 423/717; 502/232; 502/355; 502/407; 502/415; 502/527.16;
502/60; 502/8 |
Current CPC
Class: |
B01J
21/04 (20130101); B01J 21/12 (20130101); B01J
35/08 (20130101); B01J 37/0221 (20130101); C01F
7/02 (20130101); C01P 2004/32 (20130101); C01P
2004/50 (20130101); C01P 2004/52 (20130101); C01P
2004/61 (20130101); C01P 2006/21 (20130101) |
Current International
Class: |
B01J
21/04 (20060101); B01J 21/00 (20060101); B01J
21/12 (20060101); B01J 37/00 (20060101); B01J
37/02 (20060101); B01J 35/00 (20060101); B01J
35/08 (20060101); C01F 7/00 (20060101); C01F
7/02 (20060101); B01J 035/08 () |
Field of
Search: |
;423/625,626,627,628,335,328 ;502/8,527,60,415,407,232,355,439 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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5744 |
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Jan 1972 |
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JP |
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61-256921 |
|
Nov 1986 |
|
JP |
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62-167206 |
|
Jul 1987 |
|
JP |
|
Primary Examiner: Stoll; Robert L.
Attorney, Agent or Firm: De Jonghe; T. G. Cavalieri; V.
J.
Parent Case Text
This is a division of application Ser. No. 881,156, filed 7/2/86,
now U.S. Pat. No. 4,737,478.
Claims
What is claimed is:
1. A spheroidal agglomerate body having a polylobed external
surface comprising a multiplicity of closely packed contiguous,
substantially spherical agglomerates formed from micron-sized
inorganic solid particles, said substantially spherical
agglomerates each having a diameter ranging from about 0.05 mm to
0.2 mm, and said substantially spherical agglomerates being fused
together at their areas of contact to form the resultant spheroidal
polylobe agglomerate body with overall diameter of 0.5 mm or
greater.
2. A spheroidal agglomerate body in accordance with claim 1 wherein
said micron-sized inorganic solid particles are selected from the
group consisting of alumina, silica, zeolites and mixtures
thereof.
3. A spheroidal agglomerate body in accordance with claim 2 wherein
said micron-sized inorganic solid particles are alumina.
4. A spheroidal polylobe agglomerate body in accordance with claim
2 wherein said micron-sized inorganic solid particles are
zeolites.
5. A spheroidal agglomerate body in accordance with claim 2 wherein
said micron-sized inorganic solid particles are silica.
6. A spheroidal polylobe agglomerate body in accordance with claim
1 having an overall diameter of from 1 mm to 5 mm.
7. A spheroidal polylobe agglomerate body in accordance with claim
1 having an overall diameter of from of from 1 mm to 2 mm.
8. A spheroidal polylobe agglomerate body in accordance with claim
1 having an overall diameter of from 2 mm to 5 mm.
Description
FIELD OF THE INVENTION
This invention relates to the field of small spheroidal solid body
or particle preparation. More particularly, it concerns a process
for forming spheroidal solid bodies useful as adsorbents, catalysts
and catalyst supports useful in chemical processes, via
agglomeration of a suspension of solid particles. This process
produces substantially spherical or spheroidal bodies or particles
having a small substantially uniform diameter in a specified
range.
BACKGROUND OF THE INVENTION
Related Art
A wide variety of solid inorganic bodies is prepared in the
chemical process and related industries. The spherical or
spheroidal shape is useful for such bodies because of its desirable
properties, such as better packing, higher strength, less "fine"
particles, and better flow characteristics, to name a few. These
spherical or spheroidal bodies find application primarily as
catalysts, or as supports for catalysts, or as adsorbents and the
like.
A number of processes are known to form solid inorganic bodies. For
instance, in U.S. Pat. No. 3,656,901, Kummerle discloses that
silica-alumina and silica particles are gelled by adding drops of
aqueous colloidal sodium silicate or colloidal silica alumina to a
solvent, such as an alcohol, ether-alcohol or amine. However, this
patent does not disclose a method of obtaining substantially
spherical particles having a diameter in a specified range.
In U.S. Pat. No. 3,844,978, Hickson discloses a process wherein
hydrothermal crystallization is conducted using an aqueous slurry
of hydrous sols and salts. The slurry is subsequently dewatered and
dried to give solids which are then ground to a desired size. This
patent does not teach the formation of small substantially
spherical or spheroidal agglomerates.
In U.S. patent application Ser. No. 524,197, filed Aug. 18, 1983,
Hickson describes a method wherein micron-sized particles are
dispersed in a non-aqueous medium and agglomerated by the addition
of an aqueous phase in the presence of colloidal particles to give
a plastic mass which is then extruded or otherwise formed into
particulate bodies.
In U.S. Pat. No. 3,258,311, Burzynski et al disclose a process for
the formation of uniformly small spherical beads from alkali
metal-silicates. The method comprises the steps of (1) combining
the particle-forming ingredients comprising: (a) water; (b) a
compound of the general formula xR.sub.2 O.multidot.ySiO.sub.2
where R is an alkali metal and the x/y ratio is greater than 0.24
(an x/y ratio of R.sub.2 O/SiO.sub.2 which characterizes the water
soluble sodium silicates, and also generally the other water
soluble alkali silicates); (c) dilute strong aqueous acid; and (d)
an emulsifying agent; and (2) agitating the resulting mixture. The
beads are usually about 1 micron to 1.5 millimeters in diameter.
This process is disadvantageous because when it is used to make
beads larger than 1.5 mm, they are not uniform in size.
In U.S. Pat. No. 3,140,251, Plank et al disclose the formation of
spheroids by dispersing an aluminosilicate in a hydrosol, which is
obtained by reacting an alkali metal silicate with an acid or an
alkaline coagulant. The hydrosol may be dispersed through a nozzle
into a bath of oil or other water-immiscible suspending medium to
obtain spheroidally shaped bead particles of catalyst. However, the
uniformly small size of the agglomerate cannot be controlled, and
with high agitation the colloidal solution would form an
emulsion.
In U.S. Pat. No. 3,296,151, Heinze et al disclose a process in
which solid zeolite particles are wetted with water, mixed with a
binder and kneaded into a paste which is extruded or otherwise
shaped and dried. Heinze et al also disclose other agglomeration
processes, including a process in which an aqueous sol is dripped
into a water-immiscible liquid where the sol gels as it falls
through a column of liquid. In both cases, spherical zeolite
molecular sieves are produced, which have an undisclosed diameter
or range of sizes.
In U.S. Pat. No. 3,515,684, McEvoy discloses the formation of
fluidizable cracking catalyst particles. A dispersion of finely
divided plastic particles of kaolin in water are intensely agitated
in an oil to agglomerate the particles to provide a size
distribution of the order of 15 to 150 microns in diameter suitable
for catalysts for fluidized cracking. A disadvantage of this
process appears to be that it is limited to producing particles
having a diameter of 15 to 150 microns.
In U.S. Pat. No. 4,013,587, Fischer et al disclose a process for
preparing alumina-containing particles which comprise the steps of:
(a) mixing an aluminum hydroxide hydrosol with a high molecular
weight natural organic material to form a mixture; (b) introducing
the mixture in dispersed form into a water-immiscible liquid to
form gel particles at elevated temperatures; (c) aging the
particles in the liquid and then in aqueous ammonia; (d) recovering
the particles; and (e) calcining the particles. The disadvantages
of this process include the use of elevated temperatures, and use
of aqueous ammonia which can be hazardous.
In U.S. Pat. No. 2,474,911, Pierce et al teach the preparation of
micro-spherical gel particles in a continuous manner. A sol is
introduced into a water-immiscible liquid such as an oil containing
an emulsifier. The zone of turbulence is only at the bottom of a
mixing column and the flow rate of the oil in the column is
maintained to achieve continuous flow of the gel droplets. Pierce
et al do not teach the obtaining of spherical particles having a
diameter of 1-5 mm.
A few additional U.S. Patents are of interest. In U.S. Pat. No.
2,384,946, Marisic discloses the formation of generally spherical
hydrogel pellets. The pellets are obtained by spraying the hydrogel
through an orifice into a gaseous or liquid medium.
U.S. Pat. No. 2,900,349, Schwartz discloses the preparation of
inorganic oxide gels which have high resistance to attrition. In
one embodiment, Schwartz describes the preparation of hydrogel
spheroids by allowing the gel to fall or rise slowly through a
column of hydrocarbon solvent.
In U.S. Pat. No. 3,004,929, Lucas et al disclose a process for the
preparation and extrusion of silica-alumina catalyst supports. The
catalyst supports obtained are usually pellets which are not
uniformly spherical or in the size range described in the present
invention.
In Australian Patent No. 127,250, Kimerlin et al disclose the
production of finely divided gel particles which may be employed
for catalytic adsorption and other purposes. The size is reported
to be controlled by preparing inorganic gels in minute particles by
emulsifying a hydrosol as the internal phase of a water-immiscible
liquid, agitating the emulsion to prevent separation of the phases
until the hydrosol is set and separating the gel particles. The
disadvantage of this process is that the particles are of the order
of 60-100 microns and thus are much smaller than the particles
described herein.
Tauster, in the I Journal of Catalysis, Vol. 18, No. 3, pp.
358-3680 (198), discloses a process for impregnating the pores of
particles with a metal salt by suspending them in a
water-immiscible liquid, such as a hydrocarbon, and titrating the
liquid with an aqueous solution of metal salt.
C. E. Capes, in "Agglomeration in Liquid Media" in the text
Particle Size Enlargement, published by Elsevier Scientific
Publishing Company, Amsterdam, The Netherlands, 1980, reviews a
variety of applications of water-immiscible media in
particle-forming processes. However, none of the processes
disclosed by Capes, describes the steps or spheroidal product
having a uniform diameter of about 1 to 5 mm as described
herein.
In the Canadian Journal of Chemical Engineering, Vol. 47, pp.
166-170 (1969), A. F. Sirianni et al discuss a number of processes
whereby finely divided solids in liquid suspension are
agglomerated. The solids obtained may be separated as spherical
bodies without regard t a substantially uniform size.
Additional sources of background information on agglomeration
include "Agglomeration: Growing Larger in Applications and
Technology" by J. E. Browning in Chemical Engineering, pp. 147-170
(Dec. 4, 1967); H. M. Smith and I. E. Puddington, Can. J. Chem.
Eng., Vol. 38, 1916 (1960); J. R. Farrand, Can. J. Chem. Eng., Vol.
39, 94 (1961); and J. P. Sutherland, Can. J. Chem. Eng., Vol. 40,
268 (1962).
All of the art processes described hereinabove are not without some
shortcomings. For one, it is often difficult to vary the
composition and size of the solid body. Further, the products of
these processes are often fine powders or chips having mechanical
properties which may be unacceptable under the conditions of use.
The present invention provides a method for forming small
substantially spherical or spheroidal solid inorganic bodies which
are particularly useful as catalysts and catalyst supports. The
spherical or spheroidal shape provides additional strength, reduces
breakage, improves packing, and the like. These spheroidal-shaped
agglomerates have an average uniform diameter of greater than 0.5
mm, preferably between about 1 to 5 mm, and most preferably from 2
to 5 mm.
The present invention is an improvement over the agglomeration
method claimed in U.S. application Ser. No. 691,645 filed Jan. 15,
1985 with respect to making agglomerates which contain alumina. The
present agglomeration method is carried out using alumina alone or
alumina in combination with other inorganic materials, and in the
presence of an aqueous solution which contains an acidic material.
The agglomerates prepared by the present method have an increased
crush strength and depending on the strength of the acidic material
used, the agglomerates may have an increased surface area to volume
ratio overagglomerates prepared in the absence of acidic
material.
SUMMARY OF THE INVENTION
In one embodiment, the present invention concerns a process for
producing solid substantially uniformly sized spheroidal
agglomerates of alumina or a mixture of alumina and at least one
other substantially inorganic material. More specifically, the
invention is directed to a process for producing solid
substantially spherical agglomerates containing alumina which
comprises:
(a) mixing at high speed a portion of alumina or a mixture of
alumina and at least one other inorganic material in the form of
hydrophilic micron-sized particles in a water-immiscible liquid
thereby forming a dispersion;
(b) gradually adding to the dispersion an aqueous acidic phase
while continuing high-speed mixing until spheroidal
micro-agglomerates form within the water-immiscible phase;
(c) then subjecting the micro-agglomerates to agitation at a mixing
speed low enough to achieve substantially uniformly sized
spheroidal agglomerates;
(d) separating the agglomerates obtained from the water-immiscible
solvent; and
(e) drying the agglomerates to produce hardened substantially
spherical uniformly sized agglomerates. Optionally, the process may
also incorporate in step (b) in the aqueous phase, colloidal-sized
inorganic particles, and/or about 0.1 to 70% by weight of a soluble
metal salt, in which case the metal salt is incorporated into the
agglomerates.
Another embodiment of the present invention is directed to the
spheroidal agglomerates of uniform size formed by the
above-mentioned process. More specifically, this embodiment is
directed to a solid, spheroidal and uniformly sized agglomerate of
alumina having a diameter of greater than 0.5 mm, preferably from 1
to 5 mm and most preferably from 1 mm to 2 mm or from 2 to 5 mm
depending on its end use. The agglomerates of alumina may also
contain other substantially inorganic materials. These latter
agglomerates contain at least 10% by weight of alumina and
preferably at least 25% by weight of alumina. An aspect of this
embodiment is a spheroidal polylobe agglomerate of uniform size
which comprise closely packed contiguous substantially spherical
alumina agglomerates or agglomerates of a mixture of alumina and at
least one other inorganic solid, said closely packed contiguous
substantially spherical agglomerate ranging from about 0.2 mm or
less in diameter and preferably from about 0.05 mm to 0.2 mm in
diameter, and wherein the spheroidal polylobe agglomerate has an
overall particle size diameter of 0.5 mm or greater, preferably 1
mm to 5 mm and most preferably from 1 mm to 2 mm or 2 mm to 5 mm
depending on its end use. The agglomerates contain at least 10% by
weight alumina and preferably at least 25% by weight.
The spheroidal agglomerates are useful as catalysts, catalyst
supports or bases, absorbents, and the like. The spheroidal
polylobe agglomerates by virtue of their high surface area/volume
ratio are particularly useful in those reactions which tend to be
diffusion controlled such as residuum hydroprocessing. The
agglomerates having an overall particle size diameter of from about
1 mm to 2 mm are most useful as catalysts or catalyst base
materials for residuum hydroprocessing and those having diameters
of from about 2 mm to 5 mm and greater are useful as
absorbents.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of the various operations of
mixing, dispersing, agglomerating, separating, drying and recycling
of solvent in accordance with the present invention.
FIGS. 2(a) and 2(b) are optical microscope photographs of the
spheroidal agglomerates prepared according to the method of the
present invention.
DEFINITIONS
As used herein:
"Agglomerate" or "agglomeration" refers to a product (or a
technique) that combines micron sized particles to form larger
particles which are held together by a variety of physical-chemical
forces. For the purposes of this invention, the terms spheroidal
and substantially spherical are synonymous.
"Water-immiscible liquid" refers to liquids such as hydrocarbons,
fluorocarbons, halocarbons and mixtures thereof, which are soluble
in water to an extent of not greater than about 1.0% by weight.
Preferred water-immiscible liquids for use herein have a boiling
point between about 35.degree. C. and 100.degree. C. The liquids do
not dissolve or otherwise harm the hydrophobic materials lining the
mixers or tubing of particular sections of the apparatus used in
this invention.
"Hydrocarbon" or "hydrocarbon liquid" refers to a liquid
hydrocarbon having a boiling point (bp) of about 35.degree. to
100.degree. C. It includes, for example, pentane, pentene, hexane,
hexene, cyclohexane, heptane, heptene, petroleum ether of bp
30.degree. to 60.degree. C., petroleum ether of bp 50.degree. to
80.degree. C., petroleum distillate fractions of between about
50.degree. to 100.degree. C., and the like. Hydrocarbon includes
straight, branched and cyclic structures of these compounds and
mixtures thereof.
"Fluorocarbon" refers to the group of commercially available liquid
straight, branched or cyclic aliphatic compounds wherein one or
more of the protons have been replaced by fluorine. Usually an
additional one or more protons has been replaced by chlorine or
bromine. These liquids include for example, bromofluoromethane,
1,2-dichlorohexafluorocyclobutane,
1,1,2-trichloro-1,2,2-trifluoroethane,
1-bromo-1,2-dichloro-1,2,2-trifluoroethane,
1-fluoro-1,2,2-trichloroethane and the like. The boiling points of
these liquids range from bout 35.degree. C. to 100.degree. C.
Because of diminished hydrogen bonding, removal of these liquids
from the agglomerates is more easily accomplished by heating than
with hydrocarbon liquids.
"Halocarbon" refers to liquids such as straight, branched or cyclic
aliphatic compounds wherein one or more of the protons have been
replaced by a chlorine or bromine atom. These liquids include
methylene chloride chloroform, carbon tetrachloride, ethylene
dichloride, bromochloromethane, and the like. The boiling points of
these liquids range from about 35.degree. C. to 100.degree. C.
"Zeolite" includes natural and synthetic materials of hydrous,
tectosilicate minerals characterized by having an aluminosilicate
tetrahedral framework, controlled porosity, ion-exchangeable large
cations, and loosely held water molecules permitting reversible
dehydration. Examples of hydrated aluminum and calcium silicates
include CaO.multidot.2Al.sub.2 O.sub.3 .multidot.5SiO.sub.2 or
Na.sub.2 O.multidot.2Al.sub.2 O.sub.3 .multidot.5SiO.sub.2. Some
water of hydration is usually present. These materials are
extremely useful alone or with a catalyst support in refining and
reforming of petroleum. Zeolite includes, but is not limited to,
the natural zeolites, such as erionite, chabazite, active
analcites, gmelenite and mordenite, and includes as well the
multitude of synthetic or modified crystalline zeolites such as are
referred to in the trade as ZSM-11 described in U.S. Pat. No.
3,709,979; ZSM-5 and ZSM-8 described in U.S. Pat. No. 3,755,145;
zeolites A, X, Y, L, D, R, S, T described in U.S. Pat. No.
3,013,990 and patents cited therein, CZH-5 zeolite as described in
U.S. Pat. No. 4,360,419; ZSM-43 as described in U.S. Pat. No.
4,209,499; ZSM-34 as described in U.S. Pat. No. 4,086,186; and
ZSM-39 as described in U.S. Pat. No. 4,287,166. These zeolites are
intended to be descriptive, and the patents listed above are
incorporated herein by reference.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
Referring now to FIG. 1, vessel 1, usually a high-speed mixer,
[preferably a colloid mill (CHARLOTTE)], such as is manufactured by
Chemicolloid Laboratories, Inc. of 55 Herricks Road, Garden City,
New York 11040] is used for the high-speed/high-shear mixing to
perform the required dispersion of the particles, emulsification of
the aqueous phase and formation of micro-agglomerates. Vessel 1 is
fitted with a high-speed stirring means (e.g., stirrer) 2, or may
have equivalent means of achieving the necessary high-shear mixing.
Other high-speed mixers (dispersers) in the art include those
manufactured by Myers Engineering, Inc., 8376 Salt Lake Avenue,
Bell, California 90201, and homogenizer mixers by Greerco
Corporation, Executive Drive, Hudson, New Hampshire 03051.
In a preferred embodiment for the continuous production of
spheroidal catalysts and/or adsorbents, mixing vessel 1 is a
high-shear mixer, such as colloid mill. The speed of the mixer is
usually between about 2500 and 4000 revolutions per minute (rpm),
preferably about 2800 to 3000 rpm so as to produce a dispersion of
microagglomerates. The shear speed (or edge speed) can be
calculated for these stirrers by knowing the diameters of the
stirrers or mixers. Thus, for a stirrer having a 6-inch blade,
about 2500 to 4000 rpm corresponds to an edge speed of about 66.6
to 10.66 feet per second, and 2800 to 3000 rpm corresponds to about
74.6 to 80 feet per second.
The water-immiscible liquid from line 3 (makeup liquid) and line 25
(recycle liquid) is fed continuously into vessel 1. The
water-immiscible liquid may include hydrocarbons, fluorocarbons and
halocarbons as are defined herein. Preferred liquids include the
fluorocarbons, specifically the fluoroalkanes and fluorohaloalkanes
having a boiling point of about 35.degree. to 100.degree. C. The
fluorinated liquids have an added advantage because of their high
specific gravity. The agglomerates float on the surface and are
easily removed from the liquid by surface scooping and the like.
Also, the high vapor pressure of the fluorocarbons and the lack of
hydrogen bonding facilitate the removal of the solvent during the
drying process. 1,1,2-Trichloro-1,2,2-trifluoroethane and/or
1,2-dibromo-1,1,2,2-tetrafluoroethane is particularly useful as a
liquid medium.
The alumina and optionally any other inorganic materials, such as
hydrophilic micron-sized particles, and the aqueous acidic phase
are also fed continuously and simultaneously into vessel 1 through
lines 5 and 4. The high-shear mixer produces micro-agglomerates
comprising the alumina or mixture of alumina and at least one other
inorganic material and the aqueous acidic phase. Residence times of
the micro-agglomerates in vessel 1 are usually between about 0.1
and 300 seconds, depending upon the materials involved. Desirably,
the micro-agglomerates at this stage are less than 200 microns (0.2
mm) in diameter and preferably from about 0.05 mm to 0.2 mm.
Inorganic salts or reagents may be added to the aqueous phase to
enhance the catalytic activity of the finished product, e.g., salts
of Pt, Pd, Ni, Co, Mo, Sn, W, Rh, Re and the like. Alternatively,
colloidal-sized inorganic particles can also be mixed with the
aqueous phase and also fed into vessel 1. In this manner, an
intimate mixture of inorganic catalyst components (alumina, silica,
zeolites), catalytic metals and chemical modifiers is produced by
the high-shear mixing.
The relative quantities of water-immiscible liquid, alumina alone
or in combination with at least one other hydrophilic micron-sized
inorganic particle, colloidal-sized inorganic particles, and
aqueous acidic solution are those sufficient to obtain the
described agglomeration. The alumina or mixture of alumina and at
least one other hydrophilic micron-sized inorganic particles are
usually of the order of about 1 to 25 percent by weight in the
water-immiscible liquid. The colloidalsized inorganic particles may
range up to about 30% by weight and preferably from about 5% to 30%
by weight of alumina or mixture of alumina and at least one other
hydrophilic micron-sized inorganic particles, in the
agglomerate.
In a continuous process, the dispersion of micro-agglomerates is
then conveyed by line 6 to vessel 7. Vessel 7, a low-speed mixer,
is usually baffled. It contains a stirrer 8, or equivalent means,
to mix the particles at a speed sufficiently low that the particles
will grow or agglomerate to form spheroidal agglomerates of a
substantially uniform size of about 1 to 5 mm in diameter,
preferably about 1 mm to 2 mm or 2 to 5 mm in diameter depending on
its end use. In a preferred embodiment, line 6, vessel 7, and
stirrer 8 are lined or coated with a hydrophobic material. These
materials usually take the form of a hydrophobic plastic, such as
polyalkenes (i.e., polyethylene, polypropylene, polystyrene,
polyvinylchloride, polycarbonates, poly(methylmethacrylate),
TEFLON, VITON.RTM., etc. Polyethylene and TEFLON are particularly
preferred materials. Attempts to perform the present agglomeration
in a glass or metal (i.e., stainless steel) mixing vessel results
in the inorganic agglomerate "smearing" over the inner surface of
the mixing vessel causing plugging and other operational
difficulties.
Mixer 8 of low-speed agglomerator 7 has a speed of about 250 to
2000 rpm, preferably about 1000 to 2000 rpm. The residence time of
the dispersion in this low-speed agglomerator may be from about 1
minute to 30 minutes, depending upon the desired final properties
of the agglomerates. A residence time of about 5 to 10 minutes is
preferred to form the agglomerates described herein. Generally
speaking, higher speeds of 1000 to 2000 rpm and lower residence
times (less than about 5 minute) during the agglomeration in vessel
7 will produce smaller agglomerates, of the order of 1 to 3 mm in
diameter. Generally, lower speeds of the order of 250 to 1000 rpm
and longer residence times will produce larger agglomerates of the
order of 3 to 5 mm in diameter.
Alternatively in batch processing, the function of vessel 1 and
vessel 7 may be combined in one vessel having hydrophobic inner
surfaces, as described above, such that the speed is varied from
high to low over time to achieve substantially the same result as
is obtained with the two vessels. Also, in batch processing all
reagents and liquids can be added sequentially and in any order to
the same vessel to obtain substantially the same result as with the
two vessels in the continuous process described above. The
agglomerates after the low-speed agglomeration, whether continuous
or batch, are next conveyed to the solid-liquid separator 10 via
line 9. It is preferred that the line 9 and the separator (or
screen) have hydrophobic surface as is described above. The
agglomerates then do not smear and are not destroyed on the
separator.
After the separation of the agglomerates from the water-immiscible
liquid in separator 10, the separated water-immiscible liquid (or
solvent) and any residual water are conveyed through line 11 to the
water/liquid separation vessel 12. The aqueous solution containing
the acidic material is removed via line 13 and the water-immiscible
liquid is conveyed through lines 14 and 25 to be recycled into
vessel 1. This liquid may be dried to meet the requirements for
moisture for reuse in the agglomeration process.
The separated spheroidal agglomerates (which are usually about 1 to
5 mm or larger in diameter, but preferably are from about 2 to 5 mm
and most preferably 1 to 2 mm, depending upon the agglomeration
conditions and the desired end use of the agglomerate) with most of
the solvent removed are then conveyed via line 15 to a dryer 16.
The dryer is usually an industrial belt dryer but equivalent means
may be used. Line 17 is optionally available to provide a source of
air or inert gas through the dryer to facilitate the removal of the
solvent and water. The dried spheroidal agglomerates are then
conveyed using line 18 to a sizer 19 which separates the dried
agglomerates into narrower size ranges, if necessary. Useful size
ranges are between about 1 to 5 mm, preferably about 2 to 5 mm and
most preferably from about 1 to 2 mm. The agglomerates are
collected and may be calcined at elevated temperatures to remove
additional volatile materials and to further harden them before use
as catalysts or catalyst supports.
In a similar manner to the separation described above, the
separated water-immiscible liquid and aqueous solution containing
the acidic material are transmitted through line 21 to the liquid
separator vessel 22. The aqueous solution is removed via line 23
and the water-immiscible liquid is conveyed through lines 24 and 25
to be recycled into vessel 1. This liquid may be dried to meet the
requirements for moisture for reuse in the agglomeration
process.
PREFERRED EMBODIMENTS
Embodiments of the present invention include the preparation of
spheroidal agglomerates wherein, after drying, the agglomerates
have a generally uniform diameter of about 1 to 5 mm, preferably
from 1 mm to 2 mm or from 2 to 5 mm depending on end use. An
additional subgroup of embodiments includes the preparation of
those agglomerates which comprise alumina as a single material, or
a mixture of alumina and at least one other inorganic material such
as molecular sieves, e.g., zeolites, crystalline microporous
silicates, aluminophosphates, and silica-aluminophosphates,
amorphous aluminosilicates, oxides of Ti, Zr, Mg, Sn, Sr, Ge, B and
the like, and mixtures thereof, and the like, and preferably
mixtures of zeolite and/or silica in combination with alumina. The
colloidal sized inorganic particles may comprise these same
inorganic materials. These component materials may be subsequently
impregnated by metals and the like, by methods known in the art to
produce active catalysts.
Preferred embodiments of the preparation of single component
alumina agglomerates include the process where the high-speed
mixing is between about 2500 and 4000 rpm, and also where the
low-speed mixing is between about 1000 to 2000 rpm. For a batch
process, these two speeds may occur sequentially in the same
vessel.
An additional preferred embodiment of the preparation of single
component alumina agglomerates is where the water-immiscible liquid
is a fluorocarbon solvent, particularly
1,1,2-trichloro-1,2,2-trifluoroethane.
Additional embodiments of the present invention include forming
spheroidal agglomerates of alumina in mixture with at least one
other micron-sized inorganic material, wherein after removal of the
agglomerates from the separator (separator 10 of FIG. 1), the
diameter of the uncured agglomerates is about 2 to 5 mm and
preferably 2 to 4 mm.
An additional embodiment of the present invention includes forming
spheroidal agglomerates of at least two components, such as
micron-sized particles of alumina and colloidal-sized particles of
silica or zeolite.
An additional embodiment includes forming two or more component
agglomerates where the high-speed mixing is between about 2500 and
4000 rpm, and the low-speed mixing is between about 1000 to 2000
rpm. For the two-component agglomerates containing alumina, an
additional preferred embodiment of the process is the use of a
fluorocarbon as a water-immiscible liquid (or solvent),
specifically 1,1,2-trichloro-1,2,2-trifluoroethane.
In the practice of the preferred embodiment of the present
invention, the alumina or mixture of alumina and at least one other
inorganic material, such as a micron-sized zeolite or silica or
mixture thereof, are first suspended in the water-immiscible liquid
with stirring and then agglomerated by gradually adding an aqueous
acidic phase which may optionally include colloidal or subcolloidal
size particles and soluble metal salts. Also, once the solid
spheroidal products have been formed, art-known methods, such as
impregnation, vapor deposition or the like, may be employed to
deposit additional materials in or on the solid bodies.
The relative amounts of alumina or mixture of alumina and at least
one other hydrated non-colloidal (micron-sized) particles such as
silica, zeolite or mixtures thereof may be controlled. The exact
ratio of the two types of particles will depend in part on the
product being produced. Usually, there is at least 10% by weight of
alumina present in the agglomerate.
The acidic materials which are added to the aqueous solutions in
the method of this invention include both inorganic and organic
acids.
While use of an acidic material increases the strength of the
agglomerate formed, the shape and pore structure of the agglomerate
may also be affected by the strength of the acidic material used.
While not being held to theory, it appears that the alumina which
is present in the agglomerate is peptized by the acid present in
the aqueous solution, i.e., the alumina is broken down into smaller
particles by the acid.
The initial step in the agglomeration process is the formation of
micro-agglomerates of peptized alumina or mixture of peptized
alumina and at least one other inorganic material which
micro-agglomerates are in the order of 0.2 mm or less in diameter
and preferably 0.05 to 0.2 mm in diameter. The micro-agglomerates
then combine to give compact structures which retain the
substantially spherical shapes of the micro-agglomerates, i.e.,
they display spherical lobes which have the dimensions of the
micro-agglomerates.
Depending on the degree of peptization of the alumina, the overall
structure of the agglomerate, which has a diameter in the order of
0.5 mm or greater, preferably about 1 mm to 5 mm and most
preferably from about 1 mm to 2 mm and 2 mm to 5 mm depending on
its end use, will generally continue to retain the original
structure or shape of the combined micro-agglomerates, or the
overall structure can be changed to a substantially spherically
smooth shape. The degree of peptization of the alumina for the most
part is a function of acid strength and concentration.
Use of strong acids in the agglomeration process tend to yield
spheroidal agglomerates with relatively smooth surfaces, whereas
relatively weaker acids tend to give spheroidal agglomerates with
irregular or polylobular shaped surfaces.
FIGS. 2(a) and 2(b) show an optical microscope photograph of the
spheroidal agglomerates prepared according to the method of this
invention. FIG. 2(a) represents a spheroidal agglomerate prepared
from alumina and using trifluoroacetic acid, a relatively strong
acid (Example 4 hereinbelow), and FIG. 2(b) represents a spheroidal
agglomerate prepared from alumina and using trichloroacetic acid, a
weaker acid (Example 6 hereinbelow).
The lobes which are present in the spheroidal agglomerate of FIG.
2(b) are substantially solid sections that project from the bulk of
the agglomerate and each has a diameter of about 0.2 mm or less and
preferably from about 0.05 to 0.2 mm.
As mentioned hereinabove, peptization refers to the ability to
break down particles of alumina to a smaller size by treatment with
an acidic reagent. For such use, any water-soluble acidic compound,
organic or inorganic, but preferably inorganic, that can impart to
said aqueous solution, a pH below 6 can be used. Specific examples
of such water-soluble acidic materials that can be used include
inorganic acids, such as nitric acid, sulfuric acid, hydrofluoric
acid, hydrochloric acid, phosphoric acid and boric acid and the
like, organic acids, such as trifluoroacetic acid, trichloroacetic
acid, oxalic acid, citric acid, tartaric acid and formic acid and
the like, may be used. The most effective acids appear to be
monobasic, with the strong mineral acids, such as nitric and
hydrochloric being the best peptizing agents.
Peptization is used to control the pore structure and to improve
the strength of the finished agglomerate. Peptization is thus a
critical factor in the preparation of the agglomerates. In the
making of spheroidal, irregular or polylobular shaped agglomerates,
acid peptization is particularly important since this imparts the
needed strength to the agglomerate.
The concentration of acidic material relative to the amount of
alumina ranges about 1.0 to 0.1 moles of acid per 100 grams of
alumina. Generally, the stronger the acid, the better the peptizing
agent and the lesser the amount of acid required, relative to a
weaker acid.
The pKa's of several acids are given in Table 1 below.
TABLE 1 ______________________________________ Acid pKa (Acid
Strength) ______________________________________ CF.sub.3 COOH 0.0
CCl.sub.3 COOH 0.9 HNO.sub.3 -1.4 CH.sub.3 COOH 5
______________________________________
Based on acid strength, it would be expected that the degree of
peptization decreases in the following way:
For example, it has been found that HNO.sub.3 and CF.sub.3 COOH
give spheroidal smooth shaped agglomerates, whereas CCl.sub.3 COOH
and CH.sub.3 COOH give spheroidal polylobe shaped agglomerates.
While generally, acidic materials having a pKa of less than about
0.9 produce smooth spheroidal shaped agglomerates, other factors
which should also be taken into consideration with respect to
obtaining a predictable shape for the agglomerate include the
presence of other types of inorganic base material used, acid
concentration and to a lesser extent, the degree and length of time
of mixing.
With respect to agglomerate shape, it has been observed that
agglomerates prepared in the presence of relatively weak acids and
possessing the spheroidal polylobe shape are surprisingly
insensitive to agglomeration time The major change is a shift to
larger agglomerate size rather than a shift to a smoother
spheroidal shape.
This invention is further described by the following Examples which
are provided to illustrate the invention and are not to be
construed as limiting the invention's scope.
EXAMPLES
Example 1
Spherical Agglomerate of Zeolite-Alumina
(a) Ultra-Stable Y-Zeolite powder (particle size less than 10
microns) is dispersed in 1000 ml of
1,1,2-trichloro-1,2,2-trifluoroethane using a POLYTRON (Brinkman
Instruments, Model PT 10/35) high-speed mixer. The reaction vessel
is a 2L polypropylene container. Catapal Alumina, (particle size
43% less than 45 microns, 15% less than 90 microns) is added and
dispersed uniformly with the zeolite. A dilute aqueous solution of
nitric acid (0.1 molar) is slowly added dropwise to the dispersion
until micro-agglomerates are formed. The speed of the POLYTRON
mixer is about 3000 rpm. The predetermined solid portion is about
53% of the total solid plus water and nitric acid, with 10 weight
percent zeolite and 90 weight percent Catapal. The reaction mixture
is transferred to the low-speed mixer and container, in which all
exposed inner surfaces are of polypropylene, and stirred for 4
minutes at a speed of 600 rpm to obtain substantially spherical
uniformly sized small agglomerates. The agglomerates are separated
from the solvent and have a diameter of about 1 to 3 mm.
The particles are then dried (dryer 16) for 4 hours at 400.degree.
F. before calcining for 1 hour at 1000.degree. F. in dry air. The
dried agglomerate particles of 1 to 3 mm in diameter obtained are
sized using standard sieves, and readily withstand additional
ion-exchange conditions with potassium solutions and impregnation
processing steps to provide the small, spheroidal smooth
agglomerates which are useful as catalysts.
(b) 1,1,2-Trichloro-1,2,2-trifluoroethane may be substituted by
other water-immiscible liquids in this preparation. Therefore,
proceeding as described in Subpart (a) above of this Example but
substituting a volumetrically equivalent amount of pentane;
pentene; cyclohexane; hexane; heptane; heptene; octane;
pentane/heptane (50/50 by volume); petroleum ether, bp
30.degree.-60.degree. C.; petroleum ether, bp 50.degree.-80.degree.
C.; methylene chloride; chloroform; ethylene dichloride;
1,2-dibromo-1,1,2,2-tetrafluoroethane;
1-bromo-1,2-dichloro-1,2,2-difluorohexane; pentane/chloroform
(50/50 by volume); or octane/1,1,2-trichloro-1,2,2-trifluoroethane
(50/50 by volume) or mixtures thereof for
1,1,2-trichloro-1,2,2-trifluoroethane, there are obtained the
corresponding small, substantially spherical smooth agglomerates of
zeolite/alumina, which when dried are useful as catalysts.
(c) The Ultra-Stable Y-Zeolite powder (micronsized particles) in
the above procedure may be substituted by other inorganic
micron-sized materials. Therefore, proceeding as is described in
Subpart (a) above of this Example, but substituting a
stoichiometrically equivalent amount of Zeolite A; Zeolite D;
Zeolite R; Zeolite S; Zeolite T; Zeolite X; Zeolite L; ZSM-5;
ZSM-8; ZSM-11; ZSM-43; ZSM-34; ZSM-39; CZH-5; SiO.sub.2 ; TiO.sub.2
; ZrO.sub.2 ; or mixtures thereof for Ultra-Stable Y-Zeolite, there
are obtained the corresponding small, substantially spherical
agglomerates of which, when dried, are useful as catalysts or
catalyst base materials.
Example 2
A Single Solid System
(a) A commercial grade of pseudo boehmite (Versal 850, Kaiser
Chemicals) 100 gms, was dispersed at 3,000 rpm in 700 mls. of
1,1,2-trichloro-1,2,2-trifluoroethane in a teflon lined variable
speed mixer. To this dispersion was added 2.82 gm concentrated
nitric acid dissolved in 90 gms of water and mixing continued for 2
min at 3,000 rpm. The speed was then reduced to 2,000 rpm and
mixing continued for an additional five minutes to obtain
substantially spherical smooth agglomerates. The solvent was
removed by filtration and the agglomerates were dried at
400.degree. F. for 4 hours and calcined at 1200.degree. F. for 1 hr
in dry air. The calcined substantially spherical smooth
agglomerates have diameters of 1 mm to 3 mm.
(b) 1,1,2-Trichloro-1,2,2-trifluoroethane may be substituted by
other water-immiscible solvents in this preparation. Therefore,
proceeding as described in Subpart (a) above of this Example but
substituting volumetrically equivalent amount of pentane; pentene;
cyclohexane; hexane; heptane; heptene; octane; pentane/heptane
(50/50 by volume); petroleum ether, bp 30.degree.-60.degree. C.;
petroleum ether, bp 50-80.degree. C.; methylene chloride;
chloroform; ethylene dichloride;
1,2-dibromo-1,1,2,2-tetrafluoroethane;
1-bromo-1,2-dichloro-1,2,2-difluorohexane; pentane/chloroform
(50/50 by volume); or octane/1,1,2-trichloro-1,2,2-trifluoroethane
(50/50 by volume) or mixtures thereof for
1,1,2-trichloro-1,2,2-trifluoroethane, there are obtained the
corresponding small, substantially spherical smooth agglomerates of
alumina, which, when dried, are useful as catalyst bases.
(c) The nitric acid may be substituted by other acids. Therefore,
proceeding as described in Subpart (a) above of this Example but
substituting a stoichiometrically equivalent amount of HClO.sub.4 ;
H.sub.2 SO.sub.4 ; HF; HBr; HI; CF.sub.3 CO.sub.2 H or mixtures
thereof for nitric acid, there are obtained the corresponding
agglomerates, which, when sieved and dried, are useful as catalyst
bases.
Example 3
A suspension of 10 weight percent Catapal in
1,2-dibromo-1,1,2,2-tetrafluoroethane is pumped from an agitated
storage tank at 100 ml per minute, through a static mixer (Kenix
quarter inch static mixer having 21 elements). Simultaneously, an
aqueous solution containing 1 M nitric acid is also pumped through
this mixer at 11 ml per minute. This premixes the Catapal with the
aqueous phase so that the dispersion entering the high-shear mixer
is of constant composition. The high-shear mixer is a high-speed
laboratory blender modified for continuous operation. The
vertically mounted mixing chamber is constructed from a 4-inch
diameter by 5-inch long stainless steel pipe closed at both ends
with 1/8-inch stainless steel plates. The bottom plate is fitted
with the blender blade assembly. The feed inlet is in the side of
the cylindrical wall, 0.5 inch from the plate. This arrangement
ensures that the fed is injected directly into the high-shear zone
in the vicinity of the rotating blade, the operating speed of which
is 3000 rpm. The outlet is located in the center of the top flange
and is connected to the adjacent low-speed agglomerator by a short
length of quarter inch ID TEFLON tubing. The horizontally mounted
low-speed agglomerator is constructed from a 4-inch diameter by
12-inch long stainless steel pipe. The ends are sealed with 1/8 in
stainless steel flanges which house both shaft seals and externally
mounted bearings. The impeller is a 0.5-inch diameter shaft to
which is attached four sets of evenly spaced pegs, 0.25-inch
diameter and 3 inches long. These pegs provide the agitation
necessary for successful agglomeration. Power to the low-speed
agglomerator is provided by a quarter horsepower DC motor. The
speed of rotation is adjustable from 50 to 1800 rpm. With the
Catapal/nitric acid system, the speed for optimum agglomeration is
300 rpm. All internal surfaces are coated with a 1-mm thick
fluoropolymer coating (Fluoroshield Coatings, W. L. Gore and
Associates). The inlet in the low-speed agglomerator is at the
bottom of the cylindrical chamber, 1 inch from the end flange
nearest the motor. The inlet diameter is 0.25 inch. The outlet for
the agglomerates is at the other end of the cylindrical chamber,
also 1 inch from the end flange. The outlet is a 1-inch inner
diameter by 3-inch length of stainless steel tubing coated on the
inside with a 0.5 mm layer of Fluoroshield. The outlet pipe is
located on the upper surface of the cylindrical chamber and is
inclined radially at 30 degrees from the vertical. This allows
convenient discharge of the agglomerates and the organic liquid
onto a coated separator screen. With this arrangement, spheroidal
smooth agglomerates at 2 to 4 mm in diameter are produced on a
continuous basis. After vacuum drying for 2 hours at 100.degree.
C., the agglomerates are calcined at 950.degree. F. for 4 hours in
a stream of dry air to give hardened spheres resistant to crushing
and suitable as a catalyst base.
Example 4
A commercial grade of pseudoboehmite (Kaiser, Versal 250) 150 g was
dispersed in 900 ml of 1,1,2-trichloro-1,2,2-trifluoroethane using
a teflon lined variable speed mixer. To this dispersion was added
9.49 g of trifluoroacetic acid dissolved in 23.9 g of water. The
mixing was continued for 2 minutes at 3,000 rpm. An aqueous
solution of phosphomolybdic acid, 63.38 g (14.4 wt % Mo, 4.4 wt %
phosphoric acid) was then added and the mixing continued for 2
minutes at 3,000 rpm. An aqueous solution of nickel nitrate, 47.58
g (7.5 wt % Ni, 1.1 wt % acetic acid) was then added and mixed for
another 2 minutes at 3,000 rpm. The mixing speed was then reduced
to 2,000 rpm to agglomerate the small, dispersed catalyst particles
and the mixing was continued for 30 minutes. The agglomerates were
separated from the solvent by screening and after drying and
calcining give substantially spherical catalyst particles with 90
wt % being in the range 2.0 to 1.0 mm in diameter. These catalyst
particles are suitable for hydroprocessing of petroleum fractions.
An example of the spheroidal smooth shape agglomerate is shown in
FIG. 2(a).
Example 5
The same type and quantity of alumina as in Example 4 was again
dispersed in 900 ml of 1,1,2-trichloro-1,2,2-trifluoroethane. An
aqueous solution of 7.50 g of concentrated nitric acid in 30.00 g
water was then added and mixed for 2 minutes at 3,000 rpm. This
amount of acid was equivalent to the number of moles of acid in
Example 4. An aqueous solution of phosphomolybdic acid, 48.39 g (18
wt % Mo, 5.8 wt % phosphoric acid) was then added and the mixing
continued for 2 minutes at 3,000 rpm. Finally, an aqueous solution
of nickel nitrate, 42.59 g (8.4 wt % Ni, 1.3 wt % acetic acid) was
added and mixed for another 2 minutes at 3,000 rpm. The mixing
speed was reduced to 2,000 rpm to agglomerate the catalyst
particles and the mixing continued for 15 minutes. The resulting
agglomerates were substantially spherical in shape and after drying
and calcining give catalyst particles with 99 wt % being in the
range 2.0 to 0.5 mm in diameter.
Example 6
Using the procedure of Example 4 but substituting 13.60 g of
trichloroacetic acid dissolved in 23.91 g of water for the
trifluoroacetic acid (equivalent to the number of moles of acid in
Example 4) and agglomerating for 15 minutes at 2,000 rpm,
spheroidal polylobe agglomerates were produced. After drying and
calcining, strong spheroidal polylobe catalyst particles were
produced with 95 wt % being 2.0 to 0.5 mm in diameter. An example
of the spheroidal polylobe shape agglomerate is shown in FIG.
2(b).
Example 7
Versal 250 alumina, 100 g, was dispersed in 900 ml of
1,1,2-trichloro-1,2,2-trifluoroethane as in Example 4. To this
dispersion was added 75.16 g of aqueous phosphomolybdic acid (30.4
wt % Mo) and mixed for 2 minutes at 3,000 rpm. Aqueous nickel
nitrate solution (15.9 wt % Ni, 2.4 wt % acetic acid) 75.45 g, was
then added and mixed for a further 2 minutes at 3,000 rpm. The
mixing speed was reduced to 600 rpm and mixing continued for 15
minutes. This gives spheroidal polylobe agglomerates which after
drying and calcining give catalyst particles with 83 wt % being 2.0
to 1.0 mm in diameter.
Example 8
Example 7 was repeated with the low speed agglomeration continued
for 30 minutes at 600 rpm. This gave spheroidal polylobe
agglomerates which after drying and calcining gave catalyst
particles with 84 wt % being 2.0 to 1.0 mm in diameter and 87 wt %
being 2.0 to 0.5 mm in diameter.
Example 9
Example 7 was repeated with the low speed agglomeration continued
for 60 minutes at 600 rpm. This also gave spheroidal polylobe
agglomerates which after drying and calcining gave catalyst
particles with 73 wt % being 2.0 to 1.0 mm in diameter and 74 wt %
being 2.0 to 0.5 mm in diameter.
Examples 7 to 9 illustrate an unexpected result that the spheroidal
shape which contains the polylobes is not very sensitive to
agglomeration time, even though the time increased from 15 to 60
minutes. However, increasing agglomeration time changes the
catalyst size distribution, with the quantity of +2.0 mm diameter
particles increasing with time. Also, there is a concomitant
increase in the strength of the catalyst particles with increasing
agglomeration time.
Table 2 summarizes the size distribution and crush strength data
for Examples 13 to 15.
TABLE 2 ______________________________________ Effect of
Agglomeration Time on Catalyst Properties
______________________________________ Agglomeration Time, minutes
15 30 60 Agglomeration Speed, rpm 600 600 600 Wt % + 2 mm diameter
3 12.7 26.0 Wt % 2-1 mm diameter 83.4 84.2 72.9 Wt % 1-0.5 mm
diameter 13.5 3.1 1.2 Wt % -0.5 mm diameter 0.1 0.0 0.0 Crush
Strength, Kg/cm.sup.(1) 7 9 14
______________________________________ .sup.(1) Carried out on 2.0
to 1.0 mm diameter particles. Note Catalyst has 9.0 wt % Ni, 20.4
wt % Mo, 0.58 wt % P.
While only a few embodiments of the invention have been shown and
described herein, it will become apparent to those skilled in the
art that various modifications and changes can be made in the
process to prepare small spheroidal agglomerates which may be
useful as catalysts and/or catalyst base materials without
departing from the spirit and scope of the present invention. All
such modifications and changes coming within the scope of the
appended claims are intended to be covered thereby.
* * * * *